Incorrect timezone when adding to calendar

What kind of field is it?

Hello,
I am having the same problem. I am using Smart Date | Default field with a start and end time selected. Timezone override - none selected. In the Date Augmenter selections I have tried the following ( Ignore the timezone if it is set to UTC?) both checked and unchecked and get the same +4 hour time jump.

here is the correct date/time from our webpage:
Wed, Jun 11 2025, 12 - 2pm

here is the ics file information:
BEGIN:VCALENDAR
PRODID:My Website
VERSION:2.0
BEGIN:VEVENT
UID:9807c4ff-71ed-4abb-8138-c0ad9a3d6407
SUMMARY:Staff Picnic
DTSTAMP:20250530T184500Z
DTSTART:20250611T200000Z
DTEND:20250611T220000Z
DESCRIPTION:This year's Staff Picnic will take place on Wednesday, June...
LOCATION:On Campus
END:VEVENT
END:VCALENDAR

Please let me know if there is a setting I am missing or if this is a problem with the module.
Thanks!
-Andrea

We are also getting reports that the timezone is one hour off for some users.

I can only test with Google Calendar and everything looks fine.

Setup:

• Default time zone: Brussels
• Server time is UTC and we have at the moment Europe/Brussels (CEST), which is +02:00 hours (I'm seeing this info in the status report under Scheduler). This is correct.
• Add to cal config: time zone override = none

Output looks fine:

https://calendar.google.com/calendar/u/0/r/eventedit?ctz=Europe/Brussels&text=Add+to+cal+test&dates=20250624T140000/20250624T160000&details=Details&location=Streetname+-+1+1000+Brussels+Belgium

BEGIN:VCALENDAR
PRODID:Client
BEGIN:VTIMEZONE
TZID:Europe/Brussels
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0200
END:STANDARD
END:VTIMEZONE
VERSION:2.0
BEGIN:VEVENT
UID:b1fdc840-6e23-4ce9-9858-95e5416237e3
SUMMARY:Add to cal test
DTSTAMP:20250618T094900Z
DTSTART;TZID=Europe/Brussels:20250624T140000
DTEND;TZID=Europe/Brussels:20250624T160000
DESCRIPTION:Description
LOCATION:RHID - Streetname 1 1000 Brussels Belgium
END:VEVENT
END:VCALENDAR

I don't see a direct solution. I can try and test with this Smart Date Format: UTC time + the Add Javascript localization option + Ignore the timezone if it is set to UTC.

Does anyone know if both anonymous and authenticated users are impacted?

I did a test with a Windows + Outlook setup (which I don't have at hand myself) and it was the same logged in and logged out. I did a test logged in with an Editor role.

The hour is indeed one hour off. On the website we have 15:00 to 16:00. When adding to Outlook on Windows a user sees 16:00 to 17:00.

When I check with Google on macOS it works fine, logged in and logged out.

@bramvandenbulcke thank you for the work you've put into testing this. When I hear about times being an hour off, I am tempted to think that it could be an issue with daylight savings time.

I came across this thread which makes it sound as though Outlook has had an issue for some time with this, but unfortunately no solution was ever provided there.

I also found this thread which shows the contents of an ics file that includes a section that defines sections for normal and daylight savings time:

BEGIN:STANDARD
DTSTART:20250406T030000
TZOFFSETFROM:+1100
TZOFFSETTO:+1000
TZNAME:AEST
RRULE:FREQ=YEARLY;BYMONTH=4;BYDAY=1SU
END:STANDARD

BEGIN:DAYLIGHT
DTSTART:20241006T020000
TZOFFSETFROM:+1000
TZOFFSETTO:+1100
TZNAME:AEDT
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=1SU
END:DAYLIGHT

That appears to be specifically relevant to recurring events, however, and in the context of that thread doesn't appear to be sufficient to prevent the time added in Outlook from being off.

That does give me an idea, however. What if you tried manually changing the timezone section of your ics file from this:

TZID:Europe/Brussels
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0200
END:STANDARD
END:VTIMEZONE

to this?

TZID:Europe/Brussels
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0100
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:+0200
TZOFFSETTO:+0200
END:DAYLIGHT
END:VTIMEZONE

If that works, we would need to figure out how to manually add this additional DST-related timezone information into the generated ics files.

We did a test with two ICS files, one original and one updated.

Original:

BEGIN:VCALENDAR
PRODID:Test
BEGIN:VTIMEZONE
TZID:Europe/Brussels
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0200
END:STANDARD
END:VTIMEZONE
VERSION:2.0
BEGIN:VEVENT
UID:87821e7c-1039-4063-bff1-66b79c05627e
SUMMARY:Summary text
DTSTAMP:20250625T074800Z
DTSTART;TZID=Europe/Brussels:20250708T150000
DTEND;TZID=Europe/Brussels:20250708T160000
DESCRIPTION:Description text.\n\n
END:VEVENT
END:VCALENDAR

Updated:

BEGIN:VCALENDAR
PRODID:Test
BEGIN:VTIMEZONE
TZID:Europe/Brussels
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0100
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:+0200
TZOFFSETTO:+0200
END:DAYLIGHT
END:VTIMEZONE
VERSION:2.0
BEGIN:VEVENT
UID:87821e7c-1039-4063-bff1-66b79c05627e
SUMMARY:Summary text
DTSTAMP:20250625T074800Z
DTSTART;TZID=Europe/Brussels:20250708T150000
DTEND;TZID=Europe/Brussels:20250708T160000
DESCRIPTION:Description text.\n\n
END:VEVENT
END:VCALENDAR

Both show 16:00 to 17:00 in Outlook on Windows. On Google Calendar (via Settings > Import % Export) both are correct.

Related: https://github.com/spatie/calendar-links/pull/166.

Question: are you testing the same ics file for both Apple Calendar and Outlook? By design this module generates an ics already optimized for Outlook if you click the Outlook link, so it should already be doing a lot of the things in the linked PR.

I did the testing only with the ICS for Outlook.